I'm replacing the exhaust hose that runs from the iron pipe loop to the transom on my 1980 C27. The old hose is really deteriorated and has a belly in it between the loop and transom. Should this hose run straight back to the transom or should it run downhill a little? I haven't really checked the elevation of the two ends but I would assume that it would run slightly down from the engine to the transom. Can anyone confirm this?
Universal 5411 Engine Exhaust Hose
- Thread starter Ajay73
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It should run up as HIGH as you can make it.
I got this from a recent post: http://www.goodoldboat.com/reader_services/articles/Marine_exhaust.php
I got this from a recent post: http://www.goodoldboat.com/reader_services/articles/Marine_exhaust.php
Stu, go to the attached link and the C27 manuals and select the link for page 42 - 55. On page 53 it shows how my system is set up. I don't have a waterlift muffler. The exhaust hose just runs from the mixing fitting (where the exhaust manifold cooling water hose enters the 1 5/8 exhaust hose) to the transom. Also, there is a check valve in the system I think to prevent water laying in the hose to get back to the engine.
http://www.catalina27.org/
Also take a look at this. This is my exhaust "loop" as I called it. My system looks exactly like this.
http://catalina.sailboatowners.com/...mid=257&cat_id=81&aid=7292&page=article&mn=27
Check this as well.
http://www.yachtsurvey.com/exhaust_risers.htm
Go down to the paragraph that starts with "Sail Boat" (about midway down)
Here's a quote from the second paragraph in the "Sail Boat" section.
The best thing for a sail boat is to use a dry, heavily insulated exhaust riser. That means no water cooling until injecting water on the down side. The problem you see in the photo below is that the water is injected on the UP side. This will eventually make life unpleasant for you. Often combined with water lift mufflers, this can be a problem if the muffler too can fill up with water. Personally, I do not like water lift mufflers because they cause too much back pressure, among other things.There often isn't enough space to install them correctly. If a system is designed right, it doesn't need a muffler as the water in the hose will accomplish all necessary muffling
I agree with Stu - you need to have a high loop installed as high as possible before it slopes back down towards the stern transom exhaust fitting. This is necessary to prevent back flow towards the engine if you are pooped by a stern wave, etc. I doubt that there is a check valve in the exhaust line if it is so simple that there's no water muffler. I have the 5411 as well, but with a water muffler installed after the riser elbow. I have seen a few yachts with a s.s. flap mounted on the stern transom exhaust port. It would help prevent water intrusion when the engine isn't running. But I would be wary of it getting corrosion trapped behind the flap, and it would make a nice home for critters to take up shop in. I would order the replacement hose that Catalina installed. If it worked for 25+ years I'd say that it was adequate. I try to follow the KISS principle.
Page 53 shows what you described. Straight exhaust hose out the stern but no indication of a check valve. Why not copy what you have then? Now I understand your question. While it's hard to see from the diagram, the ONLY way you'll know whether it runs downhill or not is that the connection at the exhaust riser would be higher than the hole in the transom.
If, however, you have the room, I would caution to use the info I provided a try to install a loop as high as possible, for the reasons mentioned.
If, however, you have the room, I would caution to use the info I provided a try to install a loop as high as possible, for the reasons mentioned.
There is a check valve on page 53, it's item number 5, and that should stop any backflow. Why do you doubt that it has a check valve? Page 53 shows it right up against the mixing fitting. Mine is about a foot after that. I have a ss fitting on the transom with a flap to stop following seas but really the check valve would prevent that, but no harm having two protections. Did you look at the Catalina 27 owner mods? It shows the actual type loop I have. Why should I have a high loop? Wouldn't that require a lot of pressure to push water/exhaust up the loop. It's probably a moot point anyway as there is no room for any kind of loop, as the surveyor comments indicate is often the case.
Yeah, it does. Item 5. Yeah, I'm going to copy what I have but my original question was just about the belly in the line running back to the transom, that's all, and was there a need for it, but I didn't emphasize that very well. I think not. Yeah, as I said, I haven't measured the elevation of the two points with the boat at rest, but my bet is that it does run downhill slightly. Thanks.
"I would order the replacement hose that Catalina installed", per Jwroan.
I ordered the same thing from West Marine.
I ordered the same thing from West Marine.
I apologize, of course you're right about the check valve. I looked at the picture which seems to just show a hose clamp at #5, the parts list calls out a check valve there, too.
You're conclusions can't be questioned: OEM install, and the manual says it's so, and there's no room.
Goes back to my last post: why the original question if from Point A to Point B is a straight line. It goes whatever way it can, right? Or am I missing something?
The original "belly" which was most likely a dip but could have been slightly up, too, for that matter, simply means the hose was a tad too long.
You're conclusions can't be questioned: OEM install, and the manual says it's so, and there's no room.
Goes back to my last post: why the original question if from Point A to Point B is a straight line. It goes whatever way it can, right? Or am I missing something?
The original "belly" which was most likely a dip but could have been slightly up, too, for that matter, simply means the hose was a tad too long.
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